Seemingly out of nowhere, a teenager in the US suddenly started experiencing intense psychotic thoughts. With no previous signs of mental illness, psychiatrists were stumped. But in a new case report, a team of doctors argues that his acute mental illness was sparked by a cat scratch.
Reporting in the Journal of Central Nervous System Disease, doctors in the Midwest have documented a case of sudden-onset adolescent schizophrenia that's linked to a bacterial infection, most likely caught from a cat scratch.
The 14-year-old boy was described as “socially, athletically, and academically active,” and otherwise in fairly good health. Then, around October 2015, he suddenly started to show some very worrying mental health symptoms. He believed he was an “evil, damned son of the devil” and felt suicidal because he was afraid he was going to murder his family and friends. He also developed a long string of phobias and a fear that his family pet cat wanted to kill him.
Doctors were quick to admit the boy for emergency psychiatric hospitalization and put him on a prescription of antipsychotic drugs. However, the psychotic episodes continued for 18 months. While the boy’s family had some history of mental illness, there appeared to be no “smoking gun” for the sudden onset of symptoms.
Then, one physician noted the boy had “stretch mark-like” lesions along his thighs and armpit. With a new line of inquiry, doctors started to investigate whether the boy was also suffering from an infection.
The boy's blood tested positive for Bartonella henselae, the bacteria associated with an infection often contracted from a bite or scratch from a cat. Just as the doctors had suspected, the boy's family had two pet cats that had been adopted as strays in 2010.
Remarkably, the teen’s mental health made a near-complete recovery after the bacterial infection was treated with antimicrobial therapies. A major factor in his sudden-onset schizophrenia, it appears, was the bacteria. While the link is uncertain, it could suggest that the Bartonella infection itself could contribute to progressive neuropsychiatric disorders like schizophrenia. It also challenges many of the assumptions we hold about psychiatric disorders in general.
Previous research has suggested that a parasite commonly carried by cats – Toxoplasma gondii – could be associated with the development of mental health problems. It could even cause notable changes to the mindstate of its host, making them more likely to engage in risky and aggressive behavior.
“Beyond this one case, there's a lot of movement in trying to understand the potential role of viral and bacterial infections in these medically complex diseases,” lead author Dr Ed Breitschwerdt, Distinguished Professor of Internal Medicine at North Carolina State University, said in a statement. "This case gives us proof that there can be a connection, and offers an opportunity for future investigations."